Apparatus for metal wetting liners

ABSTRACT

A sonic vibratory apparatus for wetting the outer surface of a ferrous metal article located in a bath of molten nonferrous metal, and including an elongated bar, one end of which supports a pair of counterrotating air driven vibrators. A flexural member is carried by the other end of the bar and is connected to a flat annular ring having a planar surface which serves as a radiator surface. A source of compressed air is provided for driving the vibrators at a resonant standing wave frequency of the flexural member.

United States Patent inventors James 8. Walker Almont; Raymond S. Amala, Oak Park, both of Mich.

Appl. No. 853,296

Filed Aug. 27, 1969 Division of Ser. No. 450,043, Apr. 22, 1965, Pat. No. 3,505,103.

Patented Nov. 9, 1971 Assignee General Motors Corporation Detroit, Mich.

APPARATUS FOR METAL WETTING LINERS [56] References Cited UNITED STATES PATENTS 3,084,650 4/1963 Johns 118/429 X 3,266,136 8/1966 Gutbier 228/1 X 3,277,566 10/1966 Christensen.... 228/1 UX 2,751,311 6/1956 Rosseau 118/429 X 2,815,535 12/1957 Bodine, Jr. 259/D1G. 43 2,824,543 2/1958 Brown 118/429 X 2,895,845 7/1959 Jones et a1. 118/429 X 3,166,773 1/1965 Wyczalek 259/D1G. 43 3,410,534 11/1968 Wyczalek 259/72 Primary Examiner.lames Kee Chi Auorneys-.l. L. Carpenter and E. J. Biskup ABSTRACT: A sonic vibratory apparatus for wetting the outer surface of a ferrous metal article located in a bath of molten nonferrous metal, and including an elongated bar, one end of which supports a pair of counterrotating air driven vibrators. A flexural member is carried by the other end of the bar and is connected to a flat annular ring having a planar surface which serves as a radiator surface. A source of compressed air is provided for driving the vibrators at a resonant standing wave frequency of the flexural member.

PATENIEUNUV 9mm 3.618.566

SHEET 1 OF 2 SOURCE OF COMPRESSED AIR INVI'IN'IURS A T TOR/VEV APPARATUS FOR METAL WETTING LINERS This is a division of application Ser. No. 450,043, filed on Apr. 22, 1965. now U.S. Pat. No. 3,505,103.

This invention concerns an apparatus for wetting a ferrous metal article with molten aluminum and more particularly a vibratory apparatus that accelerates the aluminum wetting of a ferrous metal brake liner by using sonic vibrations.

Current production methods of wetting ferrous metal brake liners with molten aluminum under static immersion conditions require a relatively long time to obtain unifonn wetting. Therefore, in order to achieve a reasonable production output, large volumes of molten aluminum are utilized so that a number of the liners can be immersed simultaneously. In addition, conveyors and fixtures must be used to carry and immerse the parts in the large baths of metal and, as should be apparent, this type of production operation results in high maintenance costs and requires large floor areas. Another difficulty is that the conveyor systems and fixtures are subject to erosion and oxidation resulting in impurities, alloying elements, and other metallic contaminants adversely effecting the wetting characteristics of the bath and therefore unless strict control of the metal bath composition is provided, acceptable wetting cannot be realized.

Accordingly, one of the objects of the present invention is to provide an improved vibratory apparatus which can be used in a metal-wetting process.

Another object is the provision of a vibratory apparatus which efficiently utilizes vibratory energy to bond a thin layer of molten aluminum to the outer surface of a ferrous metal brake liner.

A further object is the provision of a vibratory apparatus which generates sonic standing wave vibratory energy for wetting with molten aluminum a ferrous metal ring-shaped liner which has the peripheral surface thereof formed with a multiplicity of protrusions and interstices.

A still further object is to provide a vibratory wetting apparatus which is of relatively simple low-cost construction and yet which extremely efficiently utilizes vibratory energy input to wet steel or cast iron brake liners with molten aluminum.

The above objects and others are accomplished in accordance with the present invention by a vibratory apparatus which concentrates vibratory energy within certain areas of an aluminum bath so as to realize optimum wetting of the liner. Stated broadly, in the preferred form of use, a ferrous metal brake liner is first immersed into a bath of molten aluminum after which a radiator surface of the vibratory apparatus is positioned in the molten aluminum and subjected to highfrequency resonant vibration so as to direct sonic waves into localized areas adjacent the periphery of the brake liner. The vibratory energy developed in the molten aluminum causes intense cavitation to occur in the molten aluminum resulting in improved metal bonding between the ferrous metal surface of the brake liner and the aluminum. More specifically, the sonic vibratory apparatus comprises an elongated bar, one end of which supports a pair of counterrotating air-driven vibrators. A flexural member is carried by the other end of the bar and is coupled to a flat annular surface which constitutes the radiator surface. A source of compressed air is provided for driving the vibrators at a resonant standing wave frequency of the flexural member with the outer edge of the latter located at an antinode point so that the radiator surface is subjected to highamplitude vibration.

A more complete understanding of the subject invention can be derived from the following detailed description taken in conjunction with the drawings in which:

FIG. 1 is an elevation view illustrating the vibratory ap paratus made in accordance with the invention;

FIG. 2 is a view taken on line 2--2 of FIG. 1, and

FIG. 3 shows a modified version of the lower end of the vibratory apparatus illustrated in FIG. 1.

Referring now to the drawings and more specifically FIGS. 1 and 2 thereof, a vibratory apparatus made in accordance with the invention is shown supported by a plate 12 which in turn rests on the upper end of a container 14. The container 14 is filled to a predetermined level with a molten aluminum and has the floor portion thereof formed with a boss 15 so as to suitably support and locate a ring-shaped brake liner 16 in a predetermined position preparatory to the wetting thereof. The container is made from a refractory material, such as high alumina or silicon carbide, so it can withstand the high temperatures of the molten aluminum.

The vibratory apparatus 10 comprises an elongated cylindrical force transmitting bar 18, which at its upper end is connected with a vibration generating means 20 that includes a pair of air-driven vibrators 22 and 24. The vibration generating means 20 is of a type shown in detail in FIGS. 1 and 4 of U.S. Pat. No. 3,410,534, entitled Sonic Apparatus For Wetting Metals," issued Nov. I2, 1968, and assigned to the assignee of this invention. Reference is made to the aforesaid patent for a complete understanding of the type of vibration generating means utilized with this invention; however, for present purposes, it will suffice to say that the vibrators 22 and 24 each have a cylindrical working chamber in which a cylindrical roller 26 is freely located and adapted to orbit thereabout. A plurality of jets are tangentially located about the working chamber and are adapted to direct high-velocity streams of compressed air that impinge against the peripheral surface of the roller so as to drive the latter about the working chamber and thereby produce a rotating force vector which acts against the support housing of the vibrator. Suitable passage means are provided in the bar to direct air to the jets for driving the rollers of the respective vibrators in opposite directions and therebycause all forces other than those acting along the longitudinal axis of the bar 18 to be canceled. Thus, in effect, the vibration generating means 20 incorporated with this invention produces a reciprocating force that acts along the longitudinal axis of the bar 18.

The lower end of the bar 18 extends through an opening 26 in the plate 12 and is centrally connected to a disk-shaped member 28 which is bolted adjacent the edge thereof to the upper end of an annular coupling member 30 that terminates at its lower end with a planar radiator surface 32. The member 30 is made of cast iron; however, in cases where increased durability is desired, it can be made of a ceramic material. The bar 18 is supported on the plate 12 through an isolator assembly 34 that includes a mounting plate 36. A plurality of circumferentially and equally spaced studs 38 extend downwardly from the mounting plate 36 and have the threaded ends thereof accommodated by appropriate openings 40 formed in the support plate I2 and connected to the latter by nuts 42. A coil spring 44 encircles each stud and has the upper end contacting the mounting plate 36 while the lower end is seated in a well 46 found in the surface of the support plate 12. As should be apparent, the springs 44 serve to isolate the vibratory apparatus 10 from the supporting structure and thereby preclude any loss of vibratory energy thereto during the operation of the apparatus.

Immediately above the mounting plate 36 an air manifold collar 48 is locked to the bar 18 and includes an air inlet port 50 which receives compressed air from a suitable source indicated by the numeral 52 via an air conduit 54. An air control valve 55 is interposed in the conduit 54 and serves to regulate the air flow to the vibration generating means 20. In this particular form of the apparatus. a cylindrical baffle 56 is attached to the support plate 12 by four equally spaced rods 58. 60, 62, and 64 as best seen in FIG. 2. The rods are rigidly connected at their lower ends to the baffle 56 and slidably supported at their upper ends by the support plate 12. As will be more fully understood as the description of the invention proceeds, the baffle can take other forms, the purpose thereof primarily being to act as a means for confining and reflecting vibratory energy emanating from the radiator surface 32.

In practicing the invention, the container 14 is first filled with molten aluminum to a level which assures that the upper end of the liner is submerged below the upper surface 65 of the bath but still allows sufficient room for partial submersion of the coupling member 30 as seen in FIG. I. As aforemen-.

tioned, suitable means (not shown) are utilized for maintaining the aluminum in a molten state and such means can be a channel-type induction furnace, an open hearth furnace, or a gas-fired crucible furnace. The aluminum provided in the container 14 can either be a pure aluminum or an aluminum alloy.

While maintaining the aluminum in a molten state, the brake liner 16 is immersed into the bath of aluminum and located, as shown, with its inner diameter surrounding the guide boss 15. This procedure is normally followed when the liner is made from steel; however, when made from cast iron, the peripheral surface of the liner should be cleaned preparatory to immersion so as to assure a good metallurgical bond between the dissimilar metals. There are various methods of cleaning the peripheral surface of the cast iron liner and some cleaning treatments which have been found acceptable include sandblasting, an electrolytic salt bath treatment, or mechanically cutting a thin layer of metal from the outer surface of the liner. Once the outer surface of the cast iron liner is cleaned, it is then dipped into the bath of aluminum and located in a manner as described above.

The vibratory apparatus 10 is then energized by opening the valve 55 so as to direct compressed air from the source 52 to the vibration generating means 20. Sufficient air is supplied to the vibrators 22 and 24 to enable the latter to direct force impulses through the bar 18 to the member 28 at a frequency which is in the range of the resonant frequency of the member 28 so that the latter vibrates in a standing wave form as illustrated in FIG. 1. During standing wave vibration the points of minimized vibration amplitude are termed nodes, and the points of maximized vibration amplitude are termed antinodes. When the member 28 is subjected to this form of vibration, it does not vibrate bodily or as a whole but elastically in a flexural wave form. As seen in in FIG. 1, during resonant standing wave vibration the center and the outer edges of the member 28 are located at antinode points with a nodal circle existing therebetween and passing through points N and N. Thus, the coupling member 30 is located on an antinodal circle and therefore experiences increased deflection as a result of resonant operation.

It will be understood that during production operation the vibratory apparatus 10 and the container 14 can be incorporated into a press type machine. In other words, the con tainer would be supported by the stationary or lower platen while the vibratory apparatus would be suitably mounted to the movable or upper platen coaxial with the boss 15. Thus, once the vibratory apparatus 10 is brought up to its operating frequency and the press is closed, the radiator surface 32 is immersed into the molten aluminum to a point slightly above the liner 16. it will be noted that the baffle 56 will then contact the floor of the container and be located concentric with and adjacent to the outer surface of the liner. Thus, a certain amount of the molten aluminum will be confined within the enclosure created by the baffle 56 and the vibratory energy emanating from the radiator surface 32 can now be concentrated in the area between the bafile and the peripheral surface of the liner. This permits the battle to act as a reflector of the sonic waves generated by the radiator surface 32 and serves to confine the vibratory energy to an area adjacent to the periphery of the liner and thereby produce increased cavitation which results in a wetting of the brake liner.

In one test run of the method and vibratory apparatus described above, extremely good wetting was obtained on the peripheral surface of a cast iron brake liner which was approximately 3 inches in height, had an inner diameter of 12 inches and an outer diameter of 12 A inches. An aluminum alloy was utilized for accomplishing the wetting and was composed of 9.5 percent silicon, 0.5 percent magnesium and a balance of pure aluminum. The bath of aluminum was maintained at a temperature between 1,400 and 1.450 F. Prior to wetting, the liner was cleaned by mechanically cutting a thin layer of metal from the entire outer surface of the liner. The vibratory apparatus utilized in this particular test consisted of a bar 18 having a length of 42.75 inches and a major diameter of 3.0

inches. The bar was connected to a disk-shaped member 28 which had a diameter of 14 inches, a center thickness of 1.16 inches, and tapered down to an edge thickness of 0.50 inches. The vibrators 22 and 24 were of a type that were capable of generating 1,000 pounds of force at 1,000 cycles per second. The coupling member 30 had an over-all height of 3 inches, an outer diameter of 14.75 inches with an inner diameter of 1 1.25 inches.

During the wetting process in the above-mentioned test run the radiator surface 32 of the coupling member was located approximately 0.25 inch from the upper edge of the liner. It was found that so long as this distance was in a range between 0.25 and 0.75 inch, good wetting was obtained. The inner wall of the baffle 56 was located a distance between 0.50 and 1.0 inch from the peripheral surface of the brake liner. During this particular test run, the disk-shaped member achieved resonant standing wave movement at approximately 800 cycles per second and had a peak-to-peak amplitude of approximately 0.009 inch at the antinode points. Acceleration levels of the radiator surface 32 were measured in air and found to be in the area of 300 g. and complete wetting of the peripheral surface of the brake liner was obtained in several seconds. As should be apparent, after the brake liner was wetted, as explained above, the vibratory apparatus was raised out of the aluminum bath followed by removal of the brake liner for further processing. A new brake liner can then be placed in the aluminum bath and the process repeated.

FIG. 3 shows a modified form of the coupling member which, in this case, is indicated by the numeral 66. In this form of the invention, the coupling member 66 includes a laterally extending flange 68 having a radiator surface 70 integrally fonned with a depending skirt 72 which is adapted to surround the brake liner l6 and act as a reflector in the manner of the baffle 56 incorporated with the apparatus shown in FIG. 1. Except for this difference, the vibratory apparatus is identical to that previously described and operated in a similar manner for achieving wetting of the brake liner. It will be noted that parts corresponding to those incorporated with the apparatus of FIG. 1 are identified by corresponding numerals but primed.

ln both of the embodiments of the vibratory apparatus it will be noted that the coupling member has a radiator surface which extends laterally beyond the outer diameter of the brake liner. in addition, in both cases some form of baffle or reflecting means is positioned adjacent to the periphery of the brake liner during the wetting operation so that molten aluminum is confined in a small area next to the peripheral surface of the brake liner. Thus, the sonic waves emitted from the radiator surface of the coupling member are concentrated in localized portions of the bath. It is believed that primarily because of this particular type of arrangement optimum wetting can be obtained. Another important feature of this invention is the resonant operation of the disk-shaped member 28. As alluded to hereinbefore, during resonant operation maximum vibration amplitude is realized in the elastic member accompanied by high levels of acceleration.

It has been found that the above-described method and apparatus is particularly suited for wetting ferrous metal brake liners that have the outer peripheral surface thereof formed with a multiplicity of irregular metallic protrusions and interstices. One method for forming this type of roughened surface can be found in the patent to Myers Pat. No. 2,623,809. A good wetting of a brake liner of this type cannot be obtained under static immersion conditions due to surface tension characteristics of the materials. However, with this invention the irregular surface of the liner can be readily infiltrated and wetted because the induced cavitation dislodges any foreign matter including occluded gases from the interface.

Although the invention has been described as utilizing aluminum for wetting cast iron and steel, it has also been found that other nonferrous metals, such as zinc, can also be used in this process for obtaining good wetting of the liner.

We claim:

1. Sonic vibratory apparatus for wetting the outer surface of a ferrous metal article located in a bath of nonferrous metal, comprising a flexural member, vibration generating means connected to said flexural member, a source of compressed air for driving said vibration generating means at a resonant standing wave frequency of said flexural member so as to establish at least one nodal point and one antinodal point along said member, a planar radiator surface attached to said member at an antinodal point thereof, and means for supporting said flexural member so that said radiator surface is located in said bath above said article and to one side of said outer surface for delivering high frequency vibratory energy to the molten nonferrous metal adjacent said outer surface of said article.

2. Sonic vibratory apparatus for wetting the peripheral surface of a ferrous metal brake liner located in a bath of molten nonferrous metal, comprising a flexural member, vibrationgenerating means connected to said flexural member, a source of compressed air for driving said vibration-generating means at a resonant-standing wave frequency of said flexural member so as to establish at least one nodal point and one antinodal point along said member, an annular ring connected to said flexural member at said antinodal point, and means for supporting said flexural member so that a portion of said annular ring is located in said bath above said liner and to one side of said peripheral surface for delivering high-frequency vibratory energy to the molten metal adjacent said peripheral surface of said liner.

3. Sonic vibratory apparatus for wetting the peripheral surface of a ferrous metal brake liner located in a bath of molten aluminum, comprising an elongated bar, a pair of counter rotating air-driven vibrators supported by one end of said bar, a flexural member supported by the other end of said bar, an annular coupling ring secured to said flexural member with its axis coaxial with the longitudinal axis of said bar, a source of compressed air for driving said vibrators at a resonant-standing wave frequency of said flexural member so that at least one nodal point is located between the outer end of said flexural member and the point of connection between the flexural member and the bar and the outer end of said flexural member is located at an antinode, and means for supporting said bar so that a portion of said annular ring is located in said bath above said liner for delivering high-frequency vibratory energy to the molten aluminum adjacent the peripheral surface of said liner.

4. Sonic vibratory apparatus for wetting the peripheral surface of a ferrous metal brake liner located in a bath of molten aluminum, comprising an elongated bar, a pair of counterrotating air-driven vibrators supported by one end of said bar, a disk-shaped member centrally supported by the other end of said bar, an annular coupling ring secured to said disk-shaped member with its axial coaxial with the longitudinal axis passing through the center of said bar, a source of compressed air for driving said vibrators at a resonant-standing wave frequency of said disk-shaped member so that at least one nodal circle is located between the periphery of said disk-shaped member and the center thereof and the coupling ring is located at an antinode, a baffle surrounding said brake liner, and means for supporting said bar so that a portion of said annular coupling ring is located in said bath above said liner for delivering highfrequency vibratory energy to the molten aluminum adjacent the peripheral surface of said brake liner.

5. The vibratory apparatus of claim 4 wherein said coupling ring includes a radiator surface lying in a plane perpendicular to the longitudinal axis of said bar.

6. The vibratory apparatus of claim 4 wherein said baffle is integrally formed with said annular coupling ring.

7. The vibratory apparatus of claim 4 wherein said means for supporting said bar includes an isolator assembly for precluding loss of vibratory energy during operation of the apparatus. 

2. Sonic vibratory apparatus for wetting the peripheral surface of a ferrous metal brake liner located in a bath of molten nonferrous metal, comprising a flexural member, vibration-generating means connected to said flexural member, a source of compressed air for driving said vibration-generating means at a resonant-standing wave frequency of said flexural member so as to establish at leasT one nodal point and one antinodal point along said member, an annular ring connected to said flexural member at said antinodal point, and means for supporting said flexural member so that a portion of said annular ring is located in said bath above said liner and to one side of said peripheral surface for delivering high-frequency vibratory energy to the molten metal adjacent said peripheral surface of said liner.
 3. Sonic vibratory apparatus for wetting the peripheral surface of a ferrous metal brake liner located in a bath of molten aluminum, comprising an elongated bar, a pair of counterrotating air-driven vibrators supported by one end of said bar, a flexural member supported by the other end of said bar, an annular coupling ring secured to said flexural member with its axis coaxial with the longitudinal axis of said bar, a source of compressed air for driving said vibrators at a resonant-standing wave frequency of said flexural member so that at least one nodal point is located between the outer end of said flexural member and the point of connection between the flexural member and the bar and the outer end of said flexural member is located at an antinode, and means for supporting said bar so that a portion of said annular ring is located in said bath above said liner for delivering high-frequency vibratory energy to the molten aluminum adjacent the peripheral surface of said liner.
 4. Sonic vibratory apparatus for wetting the peripheral surface of a ferrous metal brake liner located in a bath of molten aluminum, comprising an elongated bar, a pair of counterrotating air-driven vibrators supported by one end of said bar, a disk-shaped member centrally supported by the other end of said bar, an annular coupling ring secured to said disk-shaped member with its axial coaxial with the longitudinal axis passing through the center of said bar, a source of compressed air for driving said vibrators at a resonant-standing wave frequency of said disk-shaped member so that at least one nodal circle is located between the periphery of said disk-shaped member and the center thereof and the coupling ring is located at an antinode, a baffle surrounding said brake liner, and means for supporting said bar so that a portion of said annular coupling ring is located in said bath above said liner for delivering high-frequency vibratory energy to the molten aluminum adjacent the peripheral surface of said brake liner.
 5. The vibratory apparatus of claim 4 wherein said coupling ring includes a radiator surface lying in a plane perpendicular to the longitudinal axis of said bar.
 6. The vibratory apparatus of claim 4 wherein said baffle is integrally formed with said annular coupling ring.
 7. The vibratory apparatus of claim 4 wherein said means for supporting said bar includes an isolator assembly for precluding loss of vibratory energy during operation of the apparatus. 